158 MR. J. O. WESTWOOD ON THE LEPIDOPTEROUS 



nexion, differing materially from the real Rhopalocerous structure ; wliilst their con- 

 nexion with the Hesperiidae is more remote than with any other group of the Diurna, 

 in consequenee of the simple arrangement of the veins of the wings in the Hesperiidse. 

 The complicated arrangement of the wing-veins in Castnia, and the metallic gloss of the 

 very large scales (which are much larger than in any other Lepidopterous genus) with 

 which most of them are clothed, and the rich coloration of nearly all the species, in like 

 manner separate them from all the other groups of Heterocerous Lepidoptera. 



The large and robust structure of the Castnice, together with their very ample wings, 

 separate them from all the groups to which they are assimilated by their transforma- 

 tion, escept the gigantic Mepiali and Cossi, from which they are at once distinguished 

 by the veining of the wings and their clavate antennge. 



In the complicated arrangement of the wing-veins, and especially in the existence of 

 the minute supplemental postcostal cell, w^e find an approximation to the Geometridse ; 

 the details of so many species of which are illustrated by Herrich-Schaffer. But the weak 

 structure of these moths and theu' geometric larvse, destitute of several pairs of the 

 ventral pro-legs, will not allow any approximation between the Castnice and Geometrce. 



Another curious circumstance connected with the group, and which is not without its 

 significance in respect to their general relation, is the analogical resemblance exhibited 

 by some of the species to that strange family of Butterflies, the Heliconiidse ; to these latter 

 we fiLad similar resemblances exhibited by species, not only of other Heterocera, as 

 among the Arctiidse, but also amongst the most typical of all the butterflies forming the 

 family Papilionidse, as well as amongst the Pierides and Erycinides. 



Hence with regard to the actual relations of the Castnice, in the uncertainty which 

 still exists as to the preponderance to be given to the characters derived either from the 

 immature or perfect state of the articulated animals, we can arrive at no other con- 

 clusion than that which Dr. Boisduval has given in his last work, ' Hist. Nat. des Ins. 

 Lepidopt. heteroceres :' — " Lafamille des Castnides appelees Hesperi-sphinx parrUlustre 

 LatreUle, quoiqu'elles n'aient pas plus de rapports avec les Hesperies qu'avec les 

 Sphinx. Ce sout des insectes d'une creation a part, qui sous leurs premiers ^tats, ont a 

 la fois les habitudes des Sesiides et des Zeuzerides, mais auxquels il est difficile d'assigner 

 une place" (Pref. p. iv). 



Tlie veining of the wings in this genus offers several modifications of much interest with 

 reference to the typical arrangement of these organs in the order Lepidoptera. In their 

 simplest form in the fore wings they may be thus described : — Ist. A strong simple branch- 

 less vein, running parallel with and close to the front margin of the fore wing (the costal 

 vein) ; 2nd. A vein arising close behind the base of the costal vein, but dividing into six 

 branches before reaching the extremity of the wing (the subcostal or postcostal vein and 

 its branches) ; 3rd. The strong median vein, separatuig into four branches ; 4th. The 

 subanal vein, simple and branchless, but sometimes accompanied by one or two rudimental 

 longitudinal veiu-like folds. In most iiistances, in order to give support to the middle of 

 the fore wing, there is a transverse veinlet connecting the 6th branch of the postcostal 

 {b 5*) and the 4<th branch (c 3*) of the median veins, forming a closed cell (the discoidal 

 ceU). But ia aU the famUies of Butterflies (except the PapUionidae) the median vein has 



